U.S. Provisional Application Nos. 60/878,823 and 60/878,817, both filed Jan. 5, 2007, are incorporated herein in their entirety by reference.
Many agricultural combines use a rotary threshing and/or separating system. The system typically includes at least one rotor drivingly rotated about a rotational axis within a rotor housing, the housing having a lower region including a perforated concave spaced radially outwardly of the rotor. The rotor will often have a frusto-conical inlet end having a helical flight or flights therearound for conveying a flow of crop material into the space between the rotor and the housing. The main body of the rotor will typically have an array or layout of threshing elements, including rasp bars and separating elements, particularly straight separator bars, which protrude radially outwardly therefrom into the space. The rasp bars and separator bars are configured differently, so as to perform different functions. The functions of the rasp bars include to cooperate with one or more vanes and guides typically disposed around the upper portion of the inner circumference of the rotor housing, for conveying a mat of the crop material along a generally helical path through the space, while cooperating with the vane or vanes and/or guides, and other aspects of the concave, e.g., bars, perforations and the like of the concave, to break up larger components of the crop material into its constituents, namely larger constituents or elements of crop residue commonly referred to as straw, which includes stalks, stems, cobs and the like, and smaller constituents which comprise the grain and smaller elements of material other than grain (MOG), in the well known manner.
To perform their function, rasp bars can be defined as including a plurality of serrations defining grooves therebetween, which are oriented at small acute angles to, or generally aligned with, the direction of rotation of the rotor. Straight bars, in contrast, perform more of a separating function, that is, they operate to separate the straw and smaller grain and MOG. To perform this function, straight separator bars generally include one or more bars extending perpendicular to the direction of rotation, and include a sharp edge or edges which also extend in that direction.
To aid in understanding the difference between rasp bars and straight separator bars during rotation of a rotor, the serrations of the rasp bars can be visualized as moving with and through the crop mat at no more than a small angle to a helical direction of flow thereof, in essentially a raking or threshing action, whereas the straight separator bars essentially plow the larger straw constituents of the crop mat, to carry them away from the smaller grain and MOG. The straight separator bars are also longer than the rasp bars in the axial direction of the rotor. Additionally, on the known rotor constructions, the longer straight separator bars are located nearer to the discharge end of the rotor, as opposed to nearer to the inlet end.
To facilitate the movement of the crop mat along a generally helically path along the rotor, it is known to mount the threshing and separating elements in a spaced helical pattern about the rotor. The threshing and separating elements are typically supported on brackets or mounting lugs that are welded or otherwise mounted to the outer surface of the main body of the rotor. Rasp bars are typically mounted individually on the mounting lugs, whereas known straight separator bars, as a result of their greater axial extent, require attachment to an axially spaced apart pair of adjacent mounting lugs. As a result, straight separator bars mounted across a pair of mounting lugs have been found to interrupt the helical flow of the crop mat around the rotor. In addition, because the mounting of these straight separator bars requires pairs of mounting lugs positioned and oriented in special relation one to the other, the locations of these lugs must be determined during construction of the rotor, resulting in limitations in options for placement, and number of straight separator bars, that can be used. In adverse conditions and with increased combine capacity, however, it is often desirable to increase separation capabilities without limitations.
As combines have started to utilize smaller diameter rotors within the housing (sometimes referred to as “small tube” technology), the increased space between the outer surface of the threshing and separating elements and the housing allow for a thicker crop mat. It has been noted, however, that operation with a thicker crop mat creates increased loading conditions on the axially longer straight separator bar type separating elements. The loading conditions generated by the interaction of the thicker crop mat with the outer surface of the axially longer straight separator bar, can increase stress at the separator bar attachment point on the mounting lug, which may result in increased maintenance requirements and/or degraded threshing performance.
Accordingly, what is sought is a straight separator bar for a threshing system of an agricultural combine which overcomes at least one of the problems, shortcomings or disadvantages set forth above.